P0350

Universal

Ignition Coil Primary/Secondary Circuit Malfunction

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The engine control module has detected a fault in the ignition coil’s electrical circuit. The coil helps create the spark that ignites the air-fuel mixture. The code does not identify a specific failed part or cylinder; the cause may be in the coil, its wiring or connections, or the control circuit. Depending on the fault, the engine may misfire, run poorly, or show no noticeable symptoms.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine is shaking badly, losing power, or the check-engine light is flashing, stop driving when it is safe to do so and arrange diagnosis. Continued driving with a severe misfire can damage the catalytic converter. Ignition systems can produce high voltage; do not handle coil wiring or components while the engine is running.

Common Symptoms

  • The check-engine light may be on, with or without other symptoms.
  • An engine misfire may cause rough running or shaking because one or more cylinders may not receive a reliable spark.
  • Reduced power or hesitation may occur if ignition is disrupted.
  • Starting may be difficult or the engine may stall if the circuit fault significantly affects ignition.
  • There may be no noticeable change in how the vehicle runs, particularly if the fault is intermittent.

Common Causes

  • A faulty ignition coil or an internal coil-circuit fault.
  • Damaged, loose, corroded, or poorly connected wiring or connectors in the coil circuit.
  • A problem with circuit power or ground, where applicable to the vehicle’s ignition design.
  • A fault in the engine control module’s coil-control circuit or its related connections.

Diagnostic Steps

  1. Record the code and any other stored codes before clearing anything; related codes can help show whether the issue affects a broader circuit or accompanies a misfire.
  2. With the engine off and cool, visually inspect accessible ignition-coil wiring and connectors for looseness, corrosion, damaged insulation, or signs of heat. Do not pull on wires or handle the circuit with the engine running.
  3. Check the vehicle’s owner information for any relevant maintenance or warning guidance, and note whether the fault appears alongside rough running, stalling, or loss of power.
  4. If the code returns or the engine runs poorly, arrange professional circuit testing rather than replacing parts based on the code alone. Avoid probing ignition components or performing high-voltage tests without the correct service information and equipment.

When to Call a Professional

A technician can check related codes and scan data, then inspect the circuit using the wiring diagram for the exact vehicle. Electrical tests can help distinguish a coil fault from a wiring, connection, power, ground, or control-module circuit issue. The code alone is not proof that the coil needs replacement.

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Commonly Asked Questions

Does P0350 prove the ignition coil is bad?

No. It identifies a detected ignition-coil circuit malfunction, but wiring, connectors, power or ground, and the control circuit may also be involved.

Does this code identify a particular cylinder?

No. The code’s definition is broad and does not specify a cylinder. Other codes and vehicle-specific diagnostic information may help narrow the issue.

Can I keep driving with P0350?

If the vehicle runs normally, seek diagnosis soon and watch for changes. If it runs roughly, loses power, stalls, or has a flashing check-engine light, stop driving when safe because a severe misfire can cause further damage.

Can I inspect the ignition wiring myself?

A visual check of accessible wiring and connectors with the engine off and cool is reasonable. Do not touch or test ignition components while the engine is running; detailed electrical testing should follow vehicle-specific service information.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.